Kim Jinyoung, Shirriff Ashley, Cornwell Jordan N, Mutis Maria Paula Quintero, Delis Ereni, Wang Sophia, Rootman Daniel B, Clites Tyler R
Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA 90095.
Department of Ophthalmic Plastic and Reconstructive Surgery, University of California Los Angeles, Los Angeles, CA 90095.
Proc Natl Acad Sci U S A. 2025 Aug 12;122(32):e2508058122. doi: 10.1073/pnas.2508058122. Epub 2025 Aug 7.
The eyelid performs critical functions to protect the eye and preserve functional vision. These functions are driven by contraction of the orbicularis oculi (OO), which is a unique skeletal muscle with a circular geometry and diffuse innervation. It is thought that this distributed innervation may allow for differential segmental activation and contraction, but it is not currently understood how sequenced activation patterns relate to differential muscle contraction, nor how segmental contraction creates the kinematics that drive the eyelid's critical functions. In fact, motion of the eyelid has predominantly been modeled in only a single dimension (open-close). Here, we show that eyelid motion has important two-dimensional features that vary between eyelid behaviors. Using distributed intramuscular electromyography, we further show that activation differs segmentally across the OO, and that patterns of activation change to produce different behavior-specific eyelid kinematics. Our results demonstrate the role of segmental activation in eyelid motion, highlighting the importance of precise neural control in producing natural eyelid behavior. We anticipate that this research is a starting point for robust mechanistic models of eyelid function. This knowledge has critical implications for diagnosis and treatment of eyelid paralysis.
眼睑执行着保护眼睛和维持功能性视力的关键功能。这些功能由眼轮匝肌（OO）的收缩驱动，眼轮匝肌是一种独特的骨骼肌，呈圆形结构且具有弥散性神经支配。据认为，这种分布式神经支配可能允许不同节段的差异性激活和收缩，但目前尚不清楚顺序激活模式如何与差异性肌肉收缩相关，也不清楚节段性收缩如何产生驱动眼睑关键功能的运动学。事实上，眼睑运动主要仅在一个维度（开合）上进行建模。在这里，我们表明眼睑运动具有重要的二维特征，这些特征在不同的眼睑行为之间有所不同。使用分布式肌内肌电图，我们进一步表明，眼轮匝肌各节段的激活存在差异，并且激活模式会发生变化以产生不同行为特异性的眼睑运动学。我们的结果证明了节段性激活在眼睑运动中的作用，突出了精确神经控制在产生自然眼睑行为中的重要性。我们预计这项研究是眼睑功能强大机制模型的起点。这一知识对眼睑麻痹的诊断和治疗具有关键意义。
